Other sugars

Besides saccharose, the principal sugar of commerce is glucose, which is dealt with in detail maltose syrup and invert sugar also occur and the analyses of these are considered briefly. 

Commercial glucose, obtained by saccharification of starchy substances, is sold in the solid condition or in highly concentrated, syrupy solution the colour varies from white to brown. The samples for analysis should be taken in the manner already described for sugar or sugar syrups and should be stored in clean, dry, well-stoppered vessels. 

The determinations usually made are those of water, ash, reducing sugars and dextrin it may sometimes be necessary to determine the insoluble matter, to test for artificial sweetening substances and, especially with syrups, to determine the acidity and sulphur dioxide. 

—From 5 to 10 grams are dried in a platinum dish on a sand-bath (if syrupy, first on a water-bath), the residue being cautiously charred over a small flame and then incinerated, best in a muffle. 

If the amount of ash is large, it may be tested qualitatively, particularly for calcium sulphate and sodium chloride, which are derived from the process of manufacture. 

Sugar industries all over the world produce four basic types of sugar products granulated, brown, liquid sugar, and invert sugar. 

Granulated. Granulated sugar is pure crystalline sucrose. It can be classified into seven types of sugar based on the crystal size. Most of these 

Brown sugar. It is used in the home and food industry to develop the rich molasses-type flavor in cookies, candies, and similar products. It 

TABLE 6.3 Different Types of Granulated Sugars and Their Special Characteristics 

Regular sugar Household use, Easier for bulk handling, 

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When the formulae of other sugars are written in this way those which have the configuration... 

C. The pentose sugar of straw, cotton-seed hulls and various hemicelluloses, and of some glycosides, including the primeverosides. It is not fermentable and behaves chemically as other sugars. 

The above chemicals can be obtained by fermentation (qv) of other sugars. However, some compounds require sucrose as a unique feedstock. Examples are the polysaccharides dextran, alteman, andlevan, which are produced by specific strains of bacteria (48,54—56). Dextrans are used to make chromatographic separation media, and sulfated dextran derivatives are used as plasma extenders (41). Levans show promise as sweetness potentiators and, along with alteman, have potential as food thickeners and bulking agents in reduced-caloric foods (55,56) (see Carbohydrates). 

By taking advantage of the remarkable abihty of subtihsia [9014-01-1] to remain catalyticahy active ia anhydrous dimethylformamide, a number of carbohydrates and other sugar-related compounds have been regioselectively acylated with trichloroethyl butyrate (100). In the case of maltose [69-79-4] (76) and sahcia [138-52-3] (77), for example, acylation occurs exclusively at the C-6 positions. 

The glycolytic pathway described in this chapter begins with the breakdown of glucose, but other sugars, both simple and complex, can enter the cycle if they can be converted by appropriate enzymes to one of the intermediates of glycolysis. Figure 19.32 shows the mechanisms by which several simple metabolites can enter the glycolytic pathway. Fructose, for example, which is pro-... 

The reactivity at the C-4 position of hexose and hexoside sulfonates has been demonstrated in the gluco and galacto series and could undoubtedly be extended to other sugars as well. In another example (25), methyl 2,3-di-0-benzoyl-4-0-p-tolysulfonyl-a-D-glucopyranoside (18a) was treated with potassium thiocyanate in N,N-dimethylformamide at 140°C. for 9 hours to give the C-4 epimeric thiocyanato derivative 19 in 34% yield. The corresponding 4-p-bromobenzenesulfonate (18b) however, afforded a 55% yield of 19 in only 2% hours of reaction time. 

Disaccharides contain a glycosidic acelal bond between the anomeric carbon of one sugar and an -OH group at any position on the other sugar. A glycosidic bond between Cl of the first sugar and the -OH at C4 of the second sugar is particularly common. Such a bond is called a 1—>4 link. 

Cell lysates from mutant strains of X. campestris were incubated with radiolabelled UDP[14C] glucose or GDP[,4C] mannose, the other sugar nudeotide substrates being unlabelled. The reaction mixture was then divided into lipid and soluble fractions. Where would you expect the radiolabel to be found and what produd, if any, would you expert from strains with defidendes in the following genes ... 

Syndecans are transmembrane proteins, which are modified by the addition of heparan sulphate glycos-aminoglycan (GAG) chains and other sugars. Syndecans bind a wide variety of different ligands via their heparan sulphate chains. Binding specificities may vary depending on cell-type specific modifications of the heparan sulphate chains. 

Honey is primarily fructose and glucose (in that order), with a little sucrose (about 1 percent), less than 10 percent other sugars, and about 17 percent water. 

Maltitol is a sugar alcohol like sorbitol, mannitol, and xylitol, but it is a larger molecule. Unlike those other sugar alcohols, and menthol, maltitol does not stimulate the cold sensors in the skin, so it does not feel cool in the mouth. 

Maltitol is used in reduced-calorie foods as a sweetener. It does not promote tooth decay, and so it is used to sweeten toothpastes and mouthwash. It is especially useful in low-calorie chocolate, because it is more like sugar than other sugar alcohols. It doesn t absorb water from the air, it is stable under heating, and it has a high melting point. 

Most users do not encounter problems. It is unclear at this time whether affected individuals cease to be affected over time, as they do with sorbitol and some other sugar alcohols that produce similar problems. 

G.19 In medicine it is sometimes necessary to prepare solutions with a specific concentration of a given ion. A lab technician has made up a 100.0-mL solution containing 0.50 g of NaCl and 0.30 g of KCl, as well as glucose and other sugars. What is the concentration of chloride ions in the solution ... 

O-acetylation of the aliphatic hydroxyl groups of the ribose moiety (or other sugar moieties) to the 2, 3, 5 -tri-0-acetates ... 

Transport systems can be described in a functional sense according to the number of molecules moved and the direction of movement (Figure 41-10) or according to whether movement is toward or away from equilibrium. A uniport system moves one type of molecule bidirectionally. In cotransport systems, the transfer of one solute depends upon the stoichiometric simultaneous or sequential transfer of another solute. A symport moves these solutes in the same direction. Examples are the proton-sugar transporter in bacteria and the Na+ -sugar transporters (for glucose and certain other sugars) and Na -amino acid transporters in mammalian cells. Antiport systems move two molecules in opposite directions (eg, Na in and Ca out). 

Traditional fermentation processes can only make use of glucose, leaving other sugars present, notably xylose, untouched. This both increases the waste element and lowers the competitiveness of the process compared to petrochemical-based ethanol. 

It is puzzling that the chlorine and other halogen substituents are not known to enhance the sweetness of other sugars, such as methyl -d-glycopyranosides, a,a-trehalose, maltose, or lactose. On the contrary, all of the deoxyhalo sugar derivatives tasted were extremely bitter. The high sweetness of the deoxyhalosucroses is clearly inexplicable in terms of either... 

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